WO2022209990A1

WO2022209990A1 - Roughened copper foil, copper-clad laminate and printed wiring board

Info

Publication number: WO2022209990A1
Application number: PCT/JP2022/012433
Authority: WO
Inventors: 歩立岡; 翼加藤; 彰太川口; 博鈞楊
Original assignee: 三井金属鉱業株式会社
Priority date: 2021-03-29
Filing date: 2022-03-17
Publication date: 2022-10-06
Also published as: US12104265B2; CN117044411A; KR20230161954A; JPWO2022209990A1; TWI808701B; US20240175162A1; TW202242153A

Abstract

Provided is a roughened copper foil that has excellent transmission characteristics and suppresses the falling off of powder. This roughened copper foil has a roughened surface on at least one side. The roughened surface has a roughness slope tanθ of 0.58 or less, as calculated by the formula, Rc/(0.5×RSm), on the basis of average height Rc (μm) and average length RSm (μm) of a contour curve element, and has a sharpness index Rc×Sku, which is the product of average height Rc (μm) and kurtosis Sku, of 2.35 or less. Rc and RSm are values measured, in accordance with JIS B0601-2013, without performing cutoff using cutoff value λs and cutoff value λc, and Sku is a value measured, in accordance with ISO 25178, without performing cutoff by an S filter and an L filter.

Description

Roughened copper foil, copper clad laminate and printed wiring board

The present invention relates to roughened copper foils, copper clad laminates and printed wiring boards.

In the manufacturing process of printed wiring boards, copper foil is widely used in the form of copper-clad laminates laminated with insulating resin substrates. In this regard, it is desired that the copper foil and the insulating resin base material have high adhesive strength in order to prevent the wiring from being peeled off during the production of the printed wiring board. Therefore, in ordinary copper foils for manufacturing printed wiring boards, the bonding surface of the copper foil is roughened to form unevenness made of fine copper particles, and the unevenness is pressed into the insulating resin base material. Adhesion is improved by exerting an anchor effect.

By the way, in recent years, as the functions of portable electronic devices have become more sophisticated, the frequency of signals, whether digital or analog, has been increasing in order to process large amounts of data at high speed. It has been demanded. For such high-frequency printed wiring boards, suppression of transmission loss is desired in order to enable transmission of high-frequency signals without degrading them. A printed wiring board is equipped with a copper foil processed into a wiring pattern and an insulating base material. The main losses in transmission loss are conductor loss caused by the copper foil and dielectric loss caused by the insulating base material. is mentioned.

　Conductor loss can increase due to the skin effect of the copper foil, which becomes more pronounced at higher frequencies. Therefore, in order to suppress the transmission loss in high-frequency applications, it is required to make the roughened particles finer so as to suppress the skin effect of the copper foil. As a copper foil having such fine roughened particles, for example, Patent Document 1 (International Publication No. 2014/133164) discloses that copper particles having a particle size of 10 nm or more and 250 nm or less (e.g., substantially spherical copper particles) are attached and roughened. A surface-treated copper foil with a black roughened surface is disclosed. In addition, in Patent Document 2 (Japanese Patent Application Laid-Open No. 2011-168887), as a copper foil having excellent transmission characteristics in a high frequency range, a roughened surface having a surface roughness Rz after roughening treatment of 1.1 μm or less is provided. A roughened copper foil having

WO2014/133164 JP 2011-168887 A

As mentioned above, in order to improve the transmission characteristics (high frequency characteristics), attempts have been made to finely roughen the bonding surface of the copper foil with the insulating resin base material. However, when the fine roughening treatment is simply performed on the copper foil, there is a problem that the fine roughening particles are likely to peel off (so-called powder falling off) due to physical contact.

On the surface of the roughened copper foil, the present inventors have found that the roughness slope tan θ calculated based on the average height Rc and the average length RSm of the profile curve elements, and the average height Rc and kurtosis Sku It has been found that by controlling the calculated sharpness index within a predetermined range, it is possible to achieve both excellent transmission characteristics and suppression of powder falling off.

Therefore, an object of the present invention is to provide a roughened copper foil that achieves both excellent transmission characteristics and suppression of powder falling off.

According to one aspect of the present invention, a roughened copper foil having a roughened surface on at least one side,
The roughened surface has a roughness gradient tan θ calculated by the formula Rc/(0.5×RSm) based on the average height Rc (μm) and the average length RSm (μm) of the contour element. is 0.58 or less, and the sharpness index Rc×Sku, which is the product of the average height Rc (μm) and the kurtosis Sku, is 2.35 or less,
The Rc and RSm are values measured under conditions in which cutoff is not performed by the cutoff value λs and the cutoff value λc in accordance with JIS B0601-2013, and the Sku is S filter and L in accordance with ISO25178. A roughened copper foil is provided, which is a value measured without filter cutoff.

According to another aspect of the present invention, there is provided a copper-clad laminate comprising the roughened copper foil.

According to still another aspect of the present invention, there is provided a printed wiring board comprising the roughened copper foil.

FIG. 4 is a diagram for explaining a roughness gradient tan θ calculated by a trigonometric function; FIG.

DEFINITIONS Definitions of terms or parameters used to define the present invention are provided below.

As used herein, "average height Rc" or "Rc" is a parameter that represents the average height of profile curve elements in a reference length, measured in accordance with JIS B0601-2013.

In this specification, "average length RSm" or "RSm" is a parameter representing the average length of profile curve elements in the reference length, measured in accordance with JIS B0601-2013. The average length RSm is a parameter for evaluating the lateral size of streaks and particles, not the height of surface unevenness.

Regarding Rc and RSm, the minimum height and minimum length are specified for the peaks or valleys that constitute the contour element, and the height is 10% or less of the maximum height Rz, or the length is the reference length. Anything less than 1% is considered noise and is part of the valleys or peaks that follow it.

In this specification, the “roughness gradient tan θ” is calculated by the formula Rc/(0.5×RSm) based on the average height Rc (μm) and the average length RSm (μm) of the profile curve element. parameter.

As used herein, "Kurtosis Sku" or "Sku" is a parameter representing the sharpness of height distribution, measured in accordance with ISO25178. Sku=3 means that the height distribution is normal distribution, Sku>3 means that the surface has many sharp peaks and valleys, and Sku<3 means that the surface is flat.

As used herein, the "peakiness index" means a parameter calculated by the product of the average height Rc (μm) and the kurtosis Sku (that is, Rc×Sku).

As used herein, the term “developed area ratio Sdr of the interface” refers to how much the developed area (surface area) of the defined region increases with respect to the area of the defined region, measured in accordance with ISO 25178. is a parameter expressed in The smaller this value, the more nearly flat the surface shape is, and the Sdr of a completely flat surface is 0%. On the other hand, the larger this value, the more uneven the surface shape.

As used herein, "arithmetic mean height Sa" or "Sa" is a parameter representing the average of the absolute values of the height differences at each point with respect to the average surface of the surface, measured in accordance with ISO25178. is. That is, it corresponds to a parameter obtained by extending the arithmetic mean height Ra of the profile curve to the surface.

In this specification, the "root mean square height Sq" or "Sq" is a parameter that corresponds to the standard deviation of the distance from the average plane, measured according to ISO25178. That is, it corresponds to a parameter obtained by extending the root mean square height Rq of the profile curve to the surface.

RSm and Rc can each be calculated by measuring a surface profile of a predetermined measurement length on the roughened surface with a commercially available laser microscope. Moreover, Sku, Sdr, Sa and Sq can be calculated by measuring the surface profile of a predetermined measurement area on the roughened surface with a commercially available laser microscope. In this specification, each parameter of RSm and Rc is measured under the condition that cutoff is not performed by cutoff value λs and cutoff value λc, and each parameter of Sku, Sdr, Sa and Sq is S filter and L filter shall be measured under the conditions without cut-off by In addition, preferable measurement conditions and analysis conditions for the surface profile by the laser microscope will be shown in Examples described later.

In this specification, the "electrode surface" of the electrolytic copper foil refers to the surface that was in contact with the cathode when the electrolytic copper foil was manufactured.

In this specification, the "deposition surface" of the electrolytic copper foil refers to the surface on which electrolytic copper is deposited during the production of the electrolytic copper foil, that is, the surface that is not in contact with the cathode.

Roughened Copper Foil The copper foil of the present invention is a roughened copper foil. This roughened copper foil has a roughened surface on at least one side. This roughened surface has a roughness gradient tan θ calculated by the formula Rc/(0.5×RSm) based on the average height Rc (μm) and the average length RSm (μm) of the profile curve elements. 0.58 or less. In addition, the roughened surface has a sharpness index Rc×Sku, which is the product of the average height Rc (μm) and the kurtosis Sku, of 2.35 or less. Thus, on the surface of the roughened copper foil, the roughness slope tan θ calculated based on the average height Rc and the average length RSm of the profile curve elements, and the sharpness index calculated based on the average height Rc and the kurtosis Sku are controlled within predetermined ranges, both excellent transmission characteristics and suppression of powder falling can be achieved.

As mentioned above, in order to improve the transmission characteristics (high frequency characteristics), attempts have been made to finely roughen the bonding surface of the copper foil with the insulating resin base material. However, when a copper foil is simply subjected to a fine roughening treatment, there is a problem that powder tends to fall off. In particular, although it is conceivable to improve the transmission characteristics by subjecting the smooth electrode surface of the electrodeposited copper foil to a fine roughening treatment, the occurrence of powder drop-off can be more pronounced on such a smooth electrode surface. It is not easy to achieve both excellent transmission characteristics and suppression of powder falling off.

As a result of investigations by the present inventors on this problem, it was found that the transmission characteristics are related to the roughness gradient tan θ of the roughened surface, and that the occurrence of powder falling is related to the sharpness index of the roughened surface. found to be related. Although these mechanisms are not necessarily certain, they are thought to be as follows. Here, FIG. 1 shows the roughness gradient tan θ calculated by the trigonometric function. As shown in FIG. 1, the roughness gradient tan θ is calculated by the formula Rc/(0.5×RSm), in other words, it corresponds to the peak or valley angle on the roughened surface. That is, the smaller the roughness gradient tan θ is, the smaller this angle becomes (that is, the peaks or valleys become smoother), so that the current flows smoothly. Conversely, the greater the roughness gradient tan θ, the greater the angle, and the greater the resistance (that is, the higher the current resistance). Therefore, by controlling the roughness gradient tan θ to a small value of 0.58 or less, it is considered that excellent transmission characteristics can be realized. Also, the sharpness index corresponds to the height and sharpness of peaks or valleys on the roughened surface. That is, the larger the sharpness index, the more high and sharp peaks or valleys are present on the roughened surface. In general, the higher and sharper the peak, the more likely it is that bumps (roughened particles) on the roughened surface will break or come off. Therefore, by controlling the sharpness index to a value as small as 2.35 or less, it is believed that the bumps can be effectively prevented from breaking or coming off. As a result, according to the roughened copper foil of the present invention, it is possible to achieve both excellent transmission characteristics and suppression of powder falling off.

Therefore, the roughened surface of the roughened copper foil has a roughness gradient tan θ of 0.58 or less, preferably 0.05 or more and 0.45 or less, more preferably 0.07 or more and 0.35 or less, and further It is preferably 0.10 or more and 0.30 or less.

In addition, the roughened surface of the roughened copper foil has a sharpness index of 2.35 or less, preferably 0.05 or more and 2.00 or less, more preferably 1.00 or more and 2.00 or less, further preferably It is 1.30 or more and 2.00 or less.

The roughened copper foil preferably has a developed area ratio Sdr of the interface on the roughened surface of 15.0% or more and 30.0% or less, more preferably 15.0% or more and 28.0% or less, and further It is preferably 15.0% or more and 27.0% or less, particularly preferably 15.0% or more and 26.0% or less. When the Sdr is within the above range, more excellent transmission characteristics can be achieved while effectively preventing powder drop.

The roughened copper foil preferably has an average height Rc of 0.40 μm or more and 0.60 μm or less, more preferably 0.40 μm or more and 0.50 μm or less on the roughened surface. When Rc is within the above range, it becomes easier to control the roughness gradient tan θ and the sharpness index within the above ranges, and more excellent transmission characteristics can be achieved while effectively preventing powder falling off.

The roughened copper foil preferably has an arithmetic mean height Sa on the roughened surface of 0.15 μm or more and 0.33 μm or less, more preferably 0.15 μm or more and 0.31 μm or less, and still more preferably 0.16 μm. It is more than 0.25 μm or less. When Sa is within the above range, more excellent transmission characteristics can be achieved while effectively preventing powder falling off.

The roughened copper foil preferably has a root-mean-square height Sq of 0.23 μm or more and 0.40 μm or less, more preferably 0.23 μm or more and 0.35 μm or less, and still more preferably 0.23 μm or more and 0.35 μm or less. It is 23 μm or more and 0.28 μm or less. When Sq is within the above range, more excellent transmission characteristics can be achieved while effectively preventing powder drop.

The roughened copper foil preferably has an average length RSm of 2.80 μm or more and 6.00 μm or less, more preferably 2.80 μm or more and 5.50 μm or less, and still more preferably It is 3.50 μm or more and 4.80 μm or less. When RSm is within the above range, it becomes easier to control the roughness gradient tan θ within the above range, and the shape of peaks or valleys on the roughened surface becomes sufficiently smooth while effectively preventing powder falling off. Better transmission characteristics can be achieved.

The roughened copper foil typically has a kurtosis Sku of 2.50 or more and 4.00 or less on the roughened surface, more typically 2.70 or more and 4.00 or less, and more typically is 2.90 or more and 4.00 or less. When Sku is within the above range, it becomes easier to control the sharpness index within the above range. As described above, Sku is a parameter representing the sharpness of the height distribution, but this is a probability distribution and does not necessarily match the effect on powder falling off. In other words, it is difficult to control the occurrence of powder dropping in the roughened copper foil only with Sku. In contrast, in the present invention, by controlling the parameter (Rc × Sku), which is a combination of Rc and Sku, which is the sharpness index, within a predetermined range, powder falling off of the roughened copper foil can be effectively prevented as described above. can be suppressed.

Although the thickness of the roughened copper foil is not particularly limited, it is preferably 0.1 μm or more and 210 μm or less, more preferably 0.5 μm or more and 70 μm or less. The roughened copper foil of the present invention is not limited to the ordinary copper foil whose surface has been roughened, but the copper foil surface of the carrier-attached copper foil has been roughened or finely roughened. can be anything.

The roughened copper foil of the present invention is formed by roughening a smooth copper foil surface (for example, the electrode surface of an electrolytic copper foil) under desired low-roughening conditions to form fine roughened particles. It can be produced preferably by Therefore, according to a preferred aspect of the present invention, the roughened copper foil is an electrolytic copper foil, and the roughened surface is present on the electrode surface side of the electrolytic copper foil. The roughened copper foil may have roughened surfaces on both sides, or may have a roughened surface only on one side. The roughened surface is typically provided with a plurality of roughened particles, and preferably each of these roughened particles is made of copper particles. The copper particles may consist of metallic copper, or may consist of a copper alloy.

The roughening treatment for forming the roughened surface can be preferably carried out by forming roughening particles with copper or a copper alloy on the copper foil. The copper foil before the roughening treatment may be a non-roughened copper foil or a pre-roughened copper foil. The surface of the copper foil to be roughened preferably has a ten-point average roughness Rz measured in accordance with JIS B0601-1994 of 0.50 μm or more and 1.50 μm or less, more preferably It is 0.60 μm or more and 1.50 μm or less. Within the above range, it becomes easier to impart the surface profile required for the roughened copper foil of the present invention to the roughened surface.

The roughening treatment is performed, for example, in a copper sulfate solution containing a copper concentration of 3 g/L or more and 20 g/L or less and a sulfuric acid concentration of 50 g/L or more and 200 g/L or less at a temperature of 20° C. or more and 40° C. or less, at a temperature of 1 A/dm ² or more and 7 A. /dm ² or less. This electrolytic deposition is preferably carried out for 0.5 to 30 seconds, more preferably 1 to 30 seconds, and even more preferably 1 to 3 seconds. At this time, the roughening treatment amount (coulomb amount) represented by the product of current density (A/dm ² ) and electrolysis time (seconds) is preferably 50 C/dm ² or less, 3 C/dm ² or more and 30 C/dm 2 or less. dm ² or less is more preferable.

During the above electrolytic deposition, the following formula:
F _Cu =F _CuSO4 ×C _Cu /S
(In the formula, F _Cu is the inter-electrode copper supply amount [(g m) / (min L)], F _CuSO4 is the flow rate (m ³ /min) of the copper sulfate solution, and C _Cu is the copper concentration of the copper sulfate solution. (g/L), S is the cross-sectional area (m ² ) between the anode and the cathode)
It is preferable that the inter-electrode copper supply amount defined by More preferably, it should be 0.1 [(g·m)/(min·L)] or more and 10.0 [(g·m)/(min·L)] or less. By doing so, it becomes easier to impart the surface profile required for the roughened copper foil of the present invention to the surface of the roughened copper foil. However, the roughened copper foil according to the present invention is not limited to the method described above, and may be manufactured by any method.

The roughening treatment preferably further includes a second roughening treatment in which electrolytic deposition is performed under predetermined conditions on the surface after the roughening treatment (first roughening treatment). By performing the roughening treatment including the first roughening treatment and the second roughening treatment, it is possible to suppress the growth of the bumps in the vertical direction (height direction). It becomes easier to impart the surface profile required for the roughened copper foil of the invention. The roughening treatment amount (coulomb amount) in this second roughening treatment is preferably 85 C/dm ² or less, more preferably 30 C/dm ² or more and 80 C/dm ² or less. For other preferred conditions in the second roughening treatment, the preferred conditions described above for the first roughening treatment apply as they are.

If desired, the roughened copper foil may be subjected to antirust treatment and may have an antirust treatment layer formed thereon. The antirust treatment preferably includes plating with zinc. The plating treatment using zinc may be either zinc plating treatment or zinc alloy plating treatment, and the zinc alloy plating treatment is particularly preferably zinc-nickel alloy treatment. The zinc-nickel alloy treatment may be a plating treatment containing at least Ni and Zn, and may further contain other elements such as Sn, Cr, Co and Mo. For example, the antirust treatment layer further contains Mo in addition to Ni and Zn, so that the treated surface of the roughened copper foil has excellent adhesion to resin, chemical resistance, and heat resistance, and etching residue is removed. It becomes difficult to remain. The Ni/Zn adhesion ratio in the zinc-nickel alloy plating is preferably 1.2 to 10, more preferably 2 to 7, and still more preferably 2.7 to 4 in mass ratio. In addition, the rust prevention treatment preferably further includes chromate treatment, and this chromate treatment is more preferably performed on the surface of the plating containing zinc after the plating treatment using zinc. By doing so, the rust resistance can be further improved. A particularly preferred antirust treatment is a combination of zinc-nickel alloy plating treatment and subsequent chromate treatment.

If desired, the surface of the roughened copper foil may be treated with a silane coupling agent to form a silane coupling agent layer. As a result, moisture resistance, chemical resistance, adhesion to adhesives and the like can be improved. The silane coupling agent layer can be formed by appropriately diluting the silane coupling agent, coating it, and drying it. Examples of silane coupling agents include epoxy-functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, or 3-aminopropyltriethoxysilane, N-(2- aminoethyl)-3-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, etc. amino-functional silane coupling agents, or mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane or olefin-functional silane coupling agents such as vinyltrimethoxysilane, vinylphenyltrimethoxysilane, or 3-methacrylic acrylic functional silane coupling agents such as roxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, or imidazole functional silane coupling agents such as imidazole silane, or triazine functional silane coupling agents such as triazine silane, and the like. is mentioned.

For the reasons described above, the roughened copper foil preferably further comprises an antirust treatment layer and/or a silane coupling agent layer on the roughened surface, more preferably the antirust treatment layer and the silane coupling agent layer. Have both. The antirust layer and the silane coupling agent layer may be formed not only on the roughened surface side of the roughened copper foil, but also on the side where the roughened surface is not formed.

Copper- Clad Laminate The roughened copper foil of the present invention is preferably used for producing a copper-clad laminate for printed wiring boards. That is, according to a preferred aspect of the present invention, there is provided a copper-clad laminate comprising the roughened copper foil. By using the roughened copper foil of the present invention, it is possible to achieve both excellent transmission characteristics and high peel strength due to suppression of powder falling off in a copper-clad laminate. This copper-clad laminate comprises the roughened copper foil of the present invention and a resin layer provided in close contact with the roughened surface of the roughened copper foil. The roughened copper foil may be provided on one side of the resin layer, or may be provided on both sides. The resin layer comprises resin, preferably insulating resin. The resin layer is preferably prepreg and/or resin sheet. Prepreg is a general term for composite materials in which synthetic resin is impregnated into a base material such as a synthetic resin plate, a glass plate, a glass woven fabric, a glass non-woven fabric, or paper. Preferred examples of insulating resins include epoxy resins, cyanate resins, bismaleimide triazine resins (BT resins), polyphenylene ether resins, and phenol resins. Examples of the insulating resin forming the resin sheet include insulating resins such as epoxy resins, polyimide resins, and polyester resins. In addition, the resin layer may contain filler particles made of various inorganic particles such as silica and alumina from the viewpoint of improving insulation. Although the thickness of the resin layer is not particularly limited, it is preferably 1 μm or more and 1000 μm or less, more preferably 2 μm or more and 400 μm or less, and still more preferably 3 μm or more and 200 μm or less. The resin layer may be composed of multiple layers. A resin layer such as a prepreg and/or a resin sheet may be provided on the roughened copper foil in advance via a primer resin layer that is applied to the surface of the copper foil.

Printed Wiring Board The roughened copper foil of the present invention is preferably used for manufacturing printed wiring boards. That is, according to a preferred aspect of the present invention, there is provided a printed wiring board comprising the roughened copper foil. By using the roughened copper foil of the present invention, it is possible to achieve both excellent transmission characteristics and high peel strength due to suppression of powder falling off in printed wiring boards. The printed wiring board according to this aspect includes a layer structure in which a resin layer and a copper layer are laminated. The copper layer is a layer derived from the roughened copper foil of the present invention. Also, the resin layer is as described above for the copper-clad laminate. In any case, a known layer structure can be adopted for the printed wiring board. Specific examples of printed wiring boards include a single-sided or double-sided printed wiring board formed by bonding the roughened copper foil of the present invention to one or both sides of a prepreg to form a cured laminate, and then forming a circuit on the printed wiring board. A multilayer printed wiring board etc. are mentioned. Further, other specific examples include flexible printed wiring boards, COF, TAB tapes, etc., in which the roughened copper foil of the present invention is formed on a resin film to form a circuit. As another specific example, a resin-coated copper foil (RCC) is formed by applying the above resin layer to the roughened copper foil of the present invention, and the resin layer is used as an insulating adhesive layer and laminated on the above printed circuit board. After that, the roughened copper foil is used as all or part of the wiring layer, and the circuit is formed by the modified semi-additive method (MSAP), the subtractive method, etc., and the roughened copper foil is removed. A build-up wiring board in which a circuit is formed by a semi-additive method (SAP), and a direct build-up on wafer in which lamination of resin-coated copper foil on a semiconductor integrated circuit and circuit formation are alternately repeated.

The present invention will be explained more specifically by the following examples.

Examples 1-10
The roughened copper foil of the present invention was manufactured as follows.

(1) Production of electrolytic copper foil For Examples 1, 2 and 4 to 9, a sulfuric acid copper sulfate solution having the composition shown below was used as the copper electrolyte, a titanium electrode was used as the cathode, and DSA ( Electrolyzed at a solution temperature of 45° C. and a current density of 55 A/dm ² using a dimensionally stable anode), an electrolytic copper foil A1 having a thickness of 18 μm was obtained. At this time, an electrode whose surface was polished with a #1000 buff to adjust the ten-point average roughness Rz to 1.2 μm was used as the cathode.
<Composition of sulfuric acid copper sulfate solution>
- Copper concentration: 80g/L
- Sulfuric acid concentration: 300g/L
- Glue concentration: 5 mg / L
- Chlorine concentration: 30 mg / L

For Example 3, electrolysis was performed under the same conditions as for the electrolytic copper foil A1, except that an electrode whose surface was polished with a #2500 buff and whose ten-point average roughness Rz was adjusted to 0.8 μm was used as the cathode. to obtain an electrolytic copper foil A2 having a thickness of 18 μm.

For Example 10, an electrolytic copper foil B with a thickness of 18 μm was obtained using a sulfuric acid copper sulfate solution having the composition shown below as the copper electrolyte. At this time, conditions other than the composition of the sulfuric acid copper sulfate solution were the same as those for the electrolytic copper foil A1.
<Composition of sulfuric acid copper sulfate solution>
- Copper concentration: 80g/L
- Sulfuric acid concentration: 260g/L
- Bis (3-sulfopropyl) disulfide concentration: 30 mg / L
- Diallyldimethylammonium chloride polymer concentration: 50 mg/L
- Chlorine concentration: 40 mg / L

(2) Roughening treatment Of the electrode surface and the deposition surface of the electrodeposited copper foil described above, roughening treatment is performed on the electrode surface side for Examples 1 to 9 and on the deposition surface side for Example 10. rice field. The electrode surface of the electrolytic copper foil used in Examples 1 to 9 and the deposition surface of the electrolytic copper foil used in Example 10 are measured using a contact surface roughness meter in accordance with JIS B0601-1994. The ten-point average roughness Rz was as shown in Table 1.

For Examples 1 to 6, the following first roughening treatment and second roughening treatment were performed in this order.
- In the first roughening treatment, each of the Electrolysis was carried out under the conditions of current density, time, amount of interelectrode copper supply and coulomb amount (current density x time) shown in Table 1 for each example, followed by washing with water.
- The second roughening treatment is performed in a copper electrolytic solution for roughening treatment having the same composition as the first roughening treatment, with the current density, time, interelectrode copper supply amount and coulomb amount shown in Table 1 for each example. It was carried out by performing electrolysis under the conditions and washing with water.

For Examples 7 and 10, the following first roughening treatment, second roughening treatment and third roughening treatment were performed in this order.
- In the first roughening treatment, each of the Electrolysis was performed under the conditions of current density, time, interelectrode copper supply amount and coulomb amount shown in Table 1 for each example, followed by washing with water.
- The second roughening treatment is performed in a copper electrolytic solution for roughening treatment having the same composition as the first roughening treatment, with the current density, time, interelectrode copper supply amount and coulomb amount shown in Table 1 for each example. It was carried out by performing electrolysis under the conditions and washing with water.
- In the third roughening treatment, each of the Electrolysis was carried out under the conditions of current density, time and interelectrode copper supply amount shown in Table 1 for each example, followed by washing with water.

For Examples 8 and 9, the following roughening treatment (first roughening treatment) was performed. This roughening treatment is performed in a copper electrolytic solution for roughening treatment (copper concentration: 3 g / L or more and 20 g / L or less, sulfuric acid concentration: 50 g / L or more and 200 g / L or less, liquid temperature: 30 ° C.) for each example Electrolysis was carried out under the conditions of current density, time, interelectrode copper supply amount and coulomb amount shown in Table 1, followed by washing with water.

(3) Anticorrosion Treatment The antirust treatment shown in Table 1 was performed on the electrolytic copper foil after the roughening treatment. As this rust prevention treatment, for Examples 3 to 6 and 10, a pyrophosphate bath was used on both sides of the electrolytic copper foil, with a potassium pyrophosphate concentration of 80 g / L, a zinc concentration of 0.2 g / L, and a nickel concentration of 2 g / L. , a liquid temperature of 40° C., and a current density of 0.5 A/dm ² . On the other hand, for Examples 1, 2 and 7 to 9, potassium pyrophosphate concentration was 100 g/L, zinc concentration was 1 g/L, nickel concentration was 2 g/L, and molybdenum concentration was Zinc-nickel-molybdenum antirust treatment was performed at 1 g/L, a liquid temperature of 40° C., and a current density of 0.5 A/dm ² . The surfaces of the electrodeposited copper foils of Examples 1, 2 and 7-9 which were not subjected to the roughening treatment were subjected to zinc-nickel antirust treatment under the same conditions as in Examples 3-6 and 10.

(4) Chromate Treatment Chromate treatment was performed on both surfaces of the antirust-treated electrolytic copper foil to form a chromate layer on the antirust treatment layer. This chromate treatment was performed under the conditions of a chromic acid concentration of 1 g/L, a pH of 11, a liquid temperature of 25° C. and a current density of 1 A/dm ² .

(5) Silane Coupling Agent Treatment The chromate-treated copper foil was washed with water and then immediately treated with a silane coupling agent to adsorb the silane coupling agent onto the chromate layer on the roughened surface. This silane coupling agent treatment was carried out by spraying a solution of a silane coupling agent using pure water as a solvent onto the roughened surface by showering for adsorption treatment. The silane coupling agent was 3-aminopropyltrimethoxysilane in Examples 1, 2, 4, 6 and 7, 3-glycidoxypropyltrimethoxysilane in Examples 3 and 8-10, and 3-acryloxypropyl in Example 5. Trimethoxysilane was used. The concentration of the silane coupling agent was 3 g/L in each case. After adsorption of the silane coupling agent, water was finally evaporated by an electric heater to obtain a roughened copper foil with a predetermined thickness.

Evaluation Various evaluations shown below were performed on the manufactured roughened copper foil.

(a) Surface Characteristic Parameters of Roughened Surface The roughened surface of the roughened copper foil was measured by surface roughness analysis using a laser microscope in accordance with ISO25178 or JIS B0601-2013. Specific measurement conditions were as shown in Table 2. The surface profile of the obtained roughened surface was analyzed according to the conditions shown in Table 2, and RSm, Rc, Sdr, Sa, Sq and Sku were calculated. Further, based on the values of RSm and Rc obtained, the roughness slope tan θ (= Rc / (0.5 × RSm)) is calculated, and the sharpness index (= Rc × Sku) is calculated based on the values of Rc and Sku was calculated. The results were as shown in Table 3.

(b) Peel Strength Between Copper Foil and Substrate Two prepregs (thickness: 100 μm) mainly composed of polyphenylene ether, triallyl isocyanurate and bismaleimide resin were prepared and stacked as insulating substrates. The produced roughened copper foil is laminated on the stacked prepreg so that the roughened surface is in contact with the prepreg, and pressed at 32 kgf/cm ² and 205° C. for 120 minutes to produce a copper clad laminate. did. Next, a circuit was formed on this copper-clad laminate by an etching method to produce a test substrate having a linear circuit with a width of 3 mm. The linear circuit thus obtained was peeled off from the insulating substrate according to JIS C 5016-1994 A method (90° peeling), and the normal peel strength (kgf/cm) was measured. The results were as shown in Table 3.

(c) Transmission characteristics A base material for high frequency (MEGTRON6N manufactured by Panasonic) was prepared as an insulating resin base material. A roughened copper foil is laminated on both sides of this insulating resin substrate so that the roughened surface is in contact with the insulating resin substrate, and a vacuum press is used at a temperature of 190 ° C. for a pressing time of 120 minutes. to obtain a copper-clad laminate having an insulation thickness of 136 μm. After that, the copper-clad laminate was subjected to an etching process to obtain a transmission loss measuring board on which microstrip lines were formed so as to have a characteristic impedance of 50Ω. The transmission loss (dB/cm) at 20 GHz was measured on the obtained transmission loss measuring substrate using a network analyzer (N5225B manufactured by Keysight Technologies). The obtained transmission loss was rated and evaluated according to the following criteria. The results were as shown in Table 3.
<Transmission loss evaluation criteria>
-Evaluation A (best): transmission loss is -0.23 dB/cm or more -Evaluation B (good): transmission loss is -0.24 dB/cm or more and less than -0.23 dB/cm -Evaluation C (poor): transmission loss is less than -0.24 dB/cm

(d) Powder drop test A powder drop test of the roughened copper foil was carried out in accordance with IPC-TM-650. Specifically, a 10 cm × 3 cm filter paper (manufactured by ADVANTEC, No. 2) is placed on the roughened surface of the manufactured roughened copper foil, and 250 g of a weight of 2 cm in diameter is placed on the filter paper. The filter paper was slid 15 cm horizontally. Thereafter, the transfer state of the roughened particles (copper particles) on the surface of the filter paper was observed, and the powder drop grade (1 to 4) was determined according to the following criteria. Then, the case where the powder drop grade was 1 or 2 was regarded as acceptable, and the other cases were regarded as unacceptable. The results were as shown in Table 3.
<Powder drop grade judgment criteria>
- Grade 1: no or very little transfer of the roughening particles to the filter paper - Grade 2: some transfer of the roughening particles to the filter paper - Grade 3: moderate transfer of the roughening particles to the filter paper - Grades 4: A large amount of roughened particles are transferred to the filter paper

Claims

A roughened copper foil having a roughened surface on at least one side,
The roughened surface has a roughness gradient tan θ calculated by the formula Rc/(0.5×RSm) based on the average height Rc (μm) and the average length RSm (μm) of the contour element. is 0.58 or less, and the sharpness index Rc×Sku, which is the product of the average height Rc (μm) and the kurtosis Sku, is 2.35 or less,
The Rc and RSm are values measured under conditions in which cutoff is not performed by the cutoff value λs and the cutoff value λc in accordance with JIS B0601-2013, and the Sku is S filter and L in accordance with ISO25178. Roughened copper foil, which is a value measured without filter cutoff.
The roughened surface has an interfacial development area ratio Sdr of 15.0% or more and 30.0% or less, and the Sdr is measured in accordance with ISO 25178 under conditions where cutoff is not performed by an S filter and an L filter. The roughened copper foil according to claim 1, which is a value of
The roughened copper foil according to claim 1 or 2, wherein the roughened surface has an average height Rc of 0.40 µm or more and 0.60 µm or less.
The roughened surface has an arithmetic mean height Sa of 0.15 μm or more and 0.33 μm or less, and the Sa is a value measured in accordance with ISO 25178 without cutoff by an S filter and an L filter. The roughened copper foil according to any one of claims 1 to 3.
The roughened surface has a root-mean-square height Sq of 0.23 μm or more and 0.40 μm or less, and the Sq is a value measured under conditions in which cutoff is not performed by an S filter and an L filter in accordance with ISO 25178. The roughened copper foil according to any one of claims 1 to 4, which is
The roughened copper foil according to any one of claims 1 to 5, wherein the roughened surface has an average length RSm of 2.80 µm or more and 6.00 µm or less.
The roughened copper foil according to any one of claims 1 to 6, further comprising an antirust treatment layer and/or a silane coupling agent layer on the roughened surface.
The roughened copper foil according to any one of claims 1 to 7, wherein the roughened copper foil is an electrolytic copper foil, and the roughened surface is present on the electrode surface side of the electrolytic copper foil.
A copper clad laminate comprising the roughened copper foil according to any one of claims 1 to 8.
A printed wiring board comprising the roughened copper foil according to any one of claims 1 to 8.